JP6142589B2 - Conductivity reduction system and conductivity reduction method - Google Patents

Description

  TECHNICAL FIELD The present invention relates to a conductivity reduction system and a conductivity reduction method, and more particularly to water that is applied to pure water used in plant construction water, power generation plants, and the like and has increased conductivity due to dissolution of carbon dioxide in the air. The present invention relates to a conductivity reduction system and a method for reducing conductivity that are effective in reducing the conductivity of pure water.

  Treated water such as pure water used in plant construction water and power generation plants has a standard value for water quality management, including conductivity, to prevent corrosion of pipes and equipment. Are managed to keep within the standard value.

  For example, for pure water used as primary cooling water in nuclear power plants, the increase in conductivity contributes to stress corrosion cracking of reactor pressure vessels and reactor internals. Strictly managed to keep inside.

  An example of a process water production line for a nuclear power plant is shown in FIG. The treatment water production line 31 includes a seawater desalination device 32, a first water storage tank 33, a transfer pump 34, a desalination device 35, and a second water storage tank 36, and supplies these facilities with treated water. It is configured to be connected in series via a pipe 37.

  In the treated water production line 31 having such a configuration, primary seawater having a conductivity reduced to about 200 μS / m is produced by treating the seawater with the seawater desalination device 32, The primary pure water is stored in the first water storage tank 33, sent from the first water storage tank 33 to the desalinator 35 by the transfer pump 34, and subjected to water treatment through the desalinator 35, so that the conductivity is about 20 to 50 μS / m. Secondary pure water is produced, and the secondary pure water is stored in the second water storage tank 36, and is supplied from the second water storage tank 36 to the primary cooling system 40 as primary cooling water when necessary. .

  Moreover, a fixed reference value (for example, conductivity: about 20 to 50 μS / m) is provided for the secondary pure water used as the primary cooling water, and the primary pure water and the second storage water at the outlet of the first water storage tank 33 are provided. By measuring the conductivity of the secondary pure water in the tank 36, the conductivity of the secondary pure water used as the primary cooling water is managed to be kept within the reference value.

  By the way, in the process water production line 31 having the above-described configuration, an overflow pipe 46 extending to the drain groove 48 is connected to the second water storage tank 36, and the second water storage tank 36 is connected through the overflow pipe 46. The interior is opened to the atmosphere, and surplus secondary pure water is drained into the drainage groove 48 through the overflow pipe. For this reason, air flows into the second water storage tank 36 through the overflow pipe 46, and carbon dioxide in the air dissolves in the secondary pure water, whereby the conductivity of the secondary pure water in the second water storage tank 36 is reached. The rate may increase and exceed the reference value.

  In this way, when the conductivity of the secondary pure water exceeds the reference value, the second water storage tank 36 is not provided with a facility for reducing the conductivity of the secondary pure water, so the conductivity has increased. It is necessary to drain the secondary pure water from the second water storage tank 36, and store the newly produced secondary pure water whose conductivity is within the reference value in the second water storage tank 36, which takes time, labor and cost. It takes.

  In order to cope with the increase in the conductivity of the secondary pure water in the second water storage tank 36 as described above, it is conceivable to apply the technique described in Patent Document 1. In the technique described in Patent Document 1, pure water in a pure water tank is pumped up and sent to a humidifier, and excess water after humidification is decompressed with a pressure regulating valve with a humidifier, and ions are removed with an ion exchange filter. It is configured to return to the pure water tank later. In addition, when the conductivity of pure water in the pure water tank exceeds the specified value due to ion elution from the atmosphere, etc., the switching valve is switched to a humidifier bypass circuit, and the pure water whose conductivity has been increased is switched to the pure water tank. Then, it is configured so as to reduce the conductivity of pure water whose conductivity has been increased by being led to an ion exchange filter through a humidifier bypass circuit.

  By applying the technique described in Patent Document 1, the second water storage tank 36 and the desalinator 35 are provided between the second water tank 36 and the inlet of the desalinator 35 in the process water production line 31 of FIG. By providing a circulation line for circulating the secondary pure water having increased conductivity between the secondary pure water and the secondary pure water, the electrical conductivity of the secondary pure water in the second water storage tank 36 can be reduced to a reference value.

  However, the technique described in Patent Document 1 requires a circulation pump that circulates secondary pure water through the circulation line, requires maintenance thereof, and labor and cost for managing the conductivity of the secondary pure water. Take it.

Japanese Patent Laid-Open No. 2004-214085

  The present invention has been made in view of the above-described conventional problems, and reduces the conductivity of treated water such as irrigated water or pure water with increased conductivity without taking time, labor, and expense. An object of the present invention is to provide a conductivity reduction system and a method for reducing conductivity.

In order to solve the above problems, the present invention employs the following means.
That is, the present invention stores the first water storage tank that stores the treated water produced by treating the raw water with water, and the treated water produced by treating the treated water in the first water storage tank, A conductivity reduction system for reducing the conductivity of treated water stored in the second water storage tank, which is used in a process water production line including a second water storage tank opened to the atmosphere, wherein the second water storage A treated water circulation pipe that connects between the bottom of the tank and the upper part of the first water storage tank, an open / close valve that opens and closes between the treated water circulation pipe and the second water storage tank, and a treatment from the first water storage tank water and a demineralizer having a detachable cartridge type ion exchange resin water treatment, Contact wherein the second water storage tank, is connected to an overflow pipe which extends up to the drainage ditch The second water storage tank through the overflow pipe have been opened to the atmosphere, with open the on-off valve, the water head pressure between the first water storage tank and the second water storage tank, said second reservoir The treated water in the tank is caused to flow toward the first water storage tank.

  According to the conductivity reduction system of the present invention, when carbon dioxide in the air is dissolved in the treated water in the second water storage tank and the conductivity of the treated water in the second water storage tank is increased, the open / close valve Is opened, the treated water circulation pipe and the second water storage tank are opened, and the treated water in the second water storage tank is removed from the first water storage tank by the head pressure between the second water storage tank and the first water storage tank. The water can be flown toward the second water tank and can be returned to the second water tank after water treatment from the first water tank. Therefore, since the treated water in the second water storage tank can be flowed to the first water storage tank without using the circulation pump, the cost required for installing the circulation pump can be reduced and the maintenance of the circulation pump can be reduced. The labor and cost required for managing the treated water in the second water storage tank can be reduced.

  In the present invention, the first water tank and the second water tank are installed on the same base, and the height of the second water tank is set higher than the height of the first water tank. It is good also as being done.

  According to the conductivity reduction system of the present invention, the first water tank and the second water tank are installed on the same base, and the height of the second water tank is set higher than the height of the first water tank. Therefore, a water head pressure can be applied between the first water storage tank and the second water storage tank, and the treated water in the second water storage tank can flow toward the first water storage tank by this water head pressure. .

  In the present invention, the connection portion of the treated water circulation pipe with the first water storage tank is provided with an inverted U-shaped upright having a height corresponding to the water level of the second water storage tank raised upward. It is good also as being done.

  According to the conductivity reduction system of the present invention, since the water level of the treated water in the second water storage tank does not drop lower than the upper part of the treated water circulation pipe, a predetermined amount of treated water is secured in the second water storage tank. can do.

  In the present invention, the treated water may be pure water used as a primary cooling water of a primary cooling system of a nuclear power plant.

  According to the conductivity reduction system of the present invention, when the conductivity of pure water increases, the conductivity of pure water used as primary cooling water can be reduced without taking time, labor, and expense. In addition, the stress corrosion cracking of the reactor pressure vessel and the reactor internal structure of the nuclear power plant can be suppressed.

The present invention also stores a first water storage tank that stores treated water produced by treating the raw water with water, and a treated water produced by treating the treated water in the first water storage tank, An electrical conductivity reducing method for reducing the electrical conductivity of treated water stored in the second water storage tank, which is used in a process water production line including a second water storage tank opened to the atmosphere . An overflow pipe extending to the drain groove is connected to the water storage tank, the inside of the second water storage tank is opened to the atmosphere through the overflow pipe, and a cartridge in which treated water from the first water storage tank can be attached and detached. The treated water produced by treating with water in a desalination apparatus having an ion exchange resin of the formula and stored in the second water storage tank is used as the second water storage tank and the first water storage water. The conductivity of the treated water stored in the second water storage tank is increased by repeatedly flowing the water toward the first water storage tank by the water head pressure between the tank and the water treatment, and then returning the water to the second water storage tank. It is characterized by reducing.

  According to the method for reducing electrical conductivity of the present invention, the electrical conductivity of the treated water in the second water storage tank having increased electrical conductivity can be reduced without taking time, labor, and expense.

  As described above, according to the conductivity reduction system and the conductivity reduction method of the present invention, the conductivity of treated water such as irrigated water or pure water whose conductivity has increased without spending time, labor, and expense. Can be reduced.

It is the block block diagram which showed one Embodiment of the electrical conductivity reduction system by this invention. It is explanatory drawing which looked at FIG. 1 from the side. It is the block block diagram which showed an example of the manufacturing line of a treated water.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
1 and 2 show an embodiment of a conductivity reduction system and a conductivity reduction method according to the present invention. The conductivity reduction system and the conductivity reduction method of the present invention are applied to treated water such as pure water used in plant construction water, power generation plant, etc., and the conductivity is increased by dissolution of carbon dioxide in the air. The present invention is effective for reducing the conductivity of treated water. In the present embodiment, the present invention is applied to a production line 1 for treated water used as a primary cooling water for a primary cooling system 10 of a nuclear power plant. Yes.

  The treated water production line 1 used as the primary cooling water 10 of the primary cooling system 10 of the nuclear power plant produces primary treated water (primary pure water) by desalinating seawater, for example, as shown in FIG. From the seawater desalination device 2, the first water storage tank 3 for storing the primary pure water from the seawater desalination device 2, the transfer pump 4 for transferring the primary pure water from the first water storage tank 3, and the first water storage tank 3 Demineralizer 5 for treating the primary pure water, a second water storage tank 6 for storing secondary treated water (secondary pure water) from the desalinator 5, and treated water for connecting these facilities in series And a supply pipe 7.

  As shown in FIG. 2, the first water storage tank 3 and the second water storage tank 6 are installed on the upper part of the same foundation 8, and the height of the first water storage tank 3 from the upper surface of the foundation 8 is set to about 2 m. The height of the second water storage tank 6 from the upper surface of the foundation 8 is set to about 10 m, and the secondary pure water from the desalinator 5 is in the second water storage tank 6 at a water level of about 8 to 9 m. It is stored in the water.

  The seawater desalination apparatus 2 includes, for example, a filtration membrane (reverse osmosis membrane), and filters and removes impurities such as salt contained in seawater by applying pressure to the seawater and passing through the filtration membrane. Primary pure water having a conductivity of about 200 (μS / m) can be produced. The primary pure water produced by the seawater desalination apparatus 2 is supplied from the seawater desalination apparatus 2 to the first water storage tank 3 and stored in the first water storage tank 3. The first water storage tank 3 is connected to a water storage tank 19 through an overflow pipe 17, and surplus primary pure water is stored in the water storage tank 19 through the overflow pipe 17.

  The desalinator 5 is provided with, for example, a removable cartridge-type ion exchange resin, and passes the primary pure water transferred from the first water storage tank 3 by the transfer pump 4 through the desalinator 5. Thus, ionic impurities (carbonate ions, compounds thereof, etc.) in the primary pure water can be removed, and secondary pure water having a conductivity of about 20 to 50 (μS / m) can be produced. . The secondary pure water that has passed through the desalting apparatus 5 is supplied from the desalting apparatus 5 to the second water storage tank 6 and stored in the second water storage tank 6. The secondary pure water stored in the second water storage tank 6 is supplied as primary cooling water from the second water storage tank 6 to the primary cooling system 10 of the plant when necessary.

  In the present embodiment, a reference value (for example, conductivity: about 20 to 50 μS / m) is provided for secondary pure water used as the primary cooling water, and the outlet of the first water storage tank 3 and the second water storage tank 6 are provided. The conductivity of the secondary pure water stored in the second water storage tank 6 is managed to be kept within the reference value by measuring the electrical conductivity of the primary pure water and the secondary pure water inside.

  By maintaining the conductivity of the secondary pure water in the second water storage tank 6 within the reference value, the increase in the conductivity of the secondary pure water used as the primary cooling water causes the reactor pressure vessel and the reactor internal structure Can suppress stress corrosion cracking.

  A first opening / closing valve 11 is provided at the inlet of the first water storage tank 3, a second opening / closing valve 12 is provided at the inlet of the second water storage tank 6, and a third opening / closing valve 13 is provided at the outlet of the second water storage tank 6 on the plant side. Each is provided. A treated water supply pipe 7 that connects between the desalinator 5 and the second water storage tank 6 is branched from the middle and connected to the filtrate water tank 9. A fourth open / close valve 14 is provided at the inlet of the filtrate water tank 9.

An overflow pipe 16 is connected to the upper portion of the second water storage tank 6, and the overflow pipe 16 extends to the drainage groove 18, and the inside of the second water storage tank 6 is opened to the atmosphere through the overflow pipe 16. Further, surplus secondary pure water in the second water storage tank 6 is drained into the drainage groove 18 through the overflow pipe 16.

  Since the overflow pipe 16 is opened to the atmosphere, air flows into the second water storage tank 6 through the overflow pipe 16 and carbon dioxide in the air is dissolved in the secondary pure water of the second water storage tank 6. As a result, the conductivity of the secondary pure water may exceed the reference value and increase to about 120 (μS / m).

  For this reason, in this Embodiment, in order to reduce the electrical conductivity of the secondary pure water in which the electrical conductivity of the 2nd water storage tank 6 rose to the reference value, the 2nd water storage tank 6 and the 1st water storage tank 3 A conductivity reduction system 20 is provided therebetween.

  The conductivity reduction system 20 opens and closes the treated water circulation pipe 21 connecting the bottom of the second water storage tank 6 and the upper part of the first water storage tank 3, and between the treated water circulation pipe 21 and the second water storage tank 6. And a fifth open / close valve 15.

  In this case, as described above, the first water storage tank 3 and the second water storage tank 6 are installed on the upper part of the same foundation 8, and the height of the first water storage tank 3 from the upper surface of the foundation 8 is set to about 2 m. In the second water storage tank 6, the height from the upper surface of the foundation 8 is set to about 10 m, and the secondary pure water level of the second water storage tank 6 is set to about 8 to 9 m. By opening the opening / closing valve 15, secondary pure water can flow from the second water storage tank 6 toward the first water storage tank 3 by water head pressure without using a pump.

  Moreover, as shown in FIG. 2, the connection part with the 1st water storage tank 3 of the treated water circulation piping 1 is started up in the shape of a reverse U, and the height from the upper surface of the foundation 8 of this upright part 22 is about 7 By setting it to about ˜8 m, the water level of the secondary pure water in the second water storage tank 6 can be kept at the same level.

  And the seawater is water-treated by the seawater desalination apparatus 2 of the treatment water production line 1 configured as described above to produce primary pure water having an electrical conductivity of about 200 (μS / m). Water is supplied to and stored in the first water storage tank 3, transferred from the first water storage tank 3 by the transfer pump 4 and passed through the desalinator 5, thereby reducing the conductivity and reducing the conductivity to about 20-50 ( secondary pure water of about μS / m) is produced, the secondary pure water is stored in the second water storage tank 6, and when necessary, the second on-off valve 13 of the second water storage tank 6 is opened to open the second water. The secondary pure water in the water storage tank 6 can be supplied to the primary cooling system 10 of the plant as primary cooling water.

  Further, the conductivity of the primary pure water and the secondary pure water is sequentially measured at the outlet of the first water storage tank 3 and inside the second water storage tank 6, and the conductivity of the secondary pure water in the second water storage tank 6 is used as a reference. By managing to maintain the value (about 20 to 50 μS / m), it is possible to suppress the occurrence of stress corrosion cracking in the reactor pressure vessel and the reactor internal structure of the plant.

  Further, when the conductivity of the secondary pure water in the second water storage tank 6 rises to a value exceeding the reference value due to dissolution of carbon dioxide in the air flowing into the second water storage tank 6 through the overflow pipe 16. The first on-off valve 11, the second on-off valve 12, the third on-off valve 13, and the fourth on-off valve 14 are closed, and the fifth on-off valve 15 of the conductivity reduction line 20 is opened.

  As a result, the secondary pure water having an increased conductivity in the second water storage tank 6 flows into the treated water circulation pipe 21 due to the water head pressure, and is returned to the first water storage tank 3 through the treated water circulation pipe 21. The secondary pure water returned to the first water storage tank 3 is supplied from the first water storage tank 3 to the desalinator 5 by the transfer pump 4, and is dissolved in the secondary pure water by passing through the desalinator 5. Ionic impurities such as carbon dioxide, hydrogen carbonate ions, carbonate ions are removed to reduce the electrical conductivity, and secondary pure water with reduced electrical conductivity is supplied to the second water storage tank 6.

  The secondary pure water is circulated between the second water storage tank 6 and the first water storage tank 3 through the treated water circulation pipe 21 a plurality of times, thereby gradually reducing the conductivity of the secondary pure water whose conductivity has been increased. The conductivity of the secondary pure water in the second water storage tank 6 can be reduced to a reference value (about 20 to 50 μS / m).

  In the conductivity reduction system and the conductivity reduction method of the present embodiment configured as described above, the bottom of the second water storage tank 6 and the top of the first water storage tank 3 of the treatment water production line 1 are provided. Since the secondary pure water flows from the second water storage tank 6 toward the first water storage tank 3 due to the head pressure, the secondary pure water whose conductivity has been increased is connected. There is no need to provide a circulation pump for circulation in the middle of the treated water circulation pipe 21.

  Therefore, it is possible to reduce the cost required for installing the circulating pump and the labor and cost required for maintaining the circulating pump, and the time, labor and cost required for the management to maintain the conductivity of the secondary pure water within the standard value can be reduced. It is possible to reduce the operation management load.

  Further, by providing the inverted U-shaped upright portion 22 at the connection portion of the treated water circulation pipe 21 with the first water storage tank 3, the water level of the secondary pure water in the second water storage tank 6 is the height of the upright portion 22. It is possible to prevent a decrease in the following, and when supplying secondary pure water as primary cooling water to the primary cooling system 10 of the plant, it is possible to prevent the amount of secondary pure water stored in the second water storage tank 6 from being insufficient. .

  In addition, it is necessary to drain the secondary pure water whose conductivity has been increased from the second water storage tank 6 and discard it, and to supply the newly produced secondary pure water whose conductivity is within the reference value to the second water storage tank 6. Therefore, the cost required for the management of the secondary pure water in the second water storage tank 6 can be reduced.

  Further, when the conductivity of the secondary pure water in the second water storage tank 6 rises and exceeds the reference value, it is only necessary to open the fifth open / close valve 15 of the treated water circulation pipe 21, so that the conductivity of the secondary pure water is sufficient. If the rate rises, you can respond quickly.

  In addition, it is not necessary to drain and discard secondary pure water having increased conductivity from the second water storage tank 6, and it is not necessary to perform chemical treatment or concentration treatment on the secondary pure water to be discarded. While being able to reduce, the safety | security of plant operation can be improved.

  In addition, since the desalting apparatus 5 is equipped with a detachable cartridge-type ion exchange resin, the maintenance of the ion exchange resin can be easily performed at a low cost. Management load can be reduced.

  In the above explanation, seawater is used as raw water and pure water is produced from seawater. However, it is applied when pure water is produced using rainwater, mountain stream water, drainage, etc. as raw water. May be.

  Further, the conductivity of the primary pure water at the outlet of the first water storage tank 3 and the secondary pure water in the second water storage tank 6 are sampled every predetermined time, and the secondary pure water in the second water storage tank 6 is sampled. When the conductivity exceeds the reference value, the fifth open / close valve 15 is opened to circulate the secondary pure water in the second water storage tank 6 through the conductivity reduction line 20, and the secondary water in the second water storage tank 6. When the conductivity of pure water is reduced to the reference value, the fifth open / close valve 15 may be automatically controlled to close.

  Further, when the secondary pure water is not supplied to the primary cooling system 10 of the plant and the second water storage tank 6 is opened to the atmosphere, the fifth open / close valve 15 is opened and the second water storage tank 6 is opened. The secondary pure water may be circulated through the conductivity reduction system 20 so as to maintain the conductivity within a reference value.

  In the above description, the conductivity reduction system and the conductivity reduction method according to the present invention are applied to the secondary pure water production line 1 used as the primary cooling water of the primary cooling system 10 of the nuclear power plant. Further, the present invention may be applied to various treated water production lines in which pure water or water treated in a tank is stored, such as a water production line for plant construction water.

DESCRIPTION OF SYMBOLS 1,31 Processed water production line 2,32 Seawater desalination apparatus 3,33 1st water storage tank 4,34 Transfer pump 5,35 Desalination equipment 6,36 2nd water storage tank 7,37 Processed water supply piping 8 Base 9 Filtration water tank 10 Primary cooling system 11 1st on-off valve 12 2nd on-off valve 13 3rd on-off valve 14 4th on-off valve 15 5th on-off valve 16, 17, 46 Overflow piping 18 Drain 19 Water tank 20 Conductivity reduction system 21 Treated water circulation piping 22 Upper part

Claims (4)

A first water storage tank that stores treated water produced by treating the raw water with water, a treated water produced by treating the treated water in the first water storage tank with water, and a second that is opened to the atmosphere. A conductivity reduction system for reducing the conductivity of the treated water stored in the second water tank, used in a treated water production line comprising a water storage tank,
A treated water circulation pipe connecting a bottom portion of the second water storage tank and an upper portion of the first water storage tank, an open / close valve for opening and closing between the treated water circulation pipe and the second water storage tank, and the first water storage tank A desalting apparatus having a detachable cartridge type ion exchange resin for treating treated water from a tank;
An overflow pipe extending to the drainage groove is connected to the second water storage tank, and the inside of the second water storage tank is opened to the atmosphere through the overflow pipe.
With the open / close valve opened, treated water in the second water storage tank is caused to flow toward the first water storage tank by a head pressure between the second water storage tank and the first water storage tank. Conductivity reduction system. The first water tank and the second water tank are installed on the same foundation, and the height of the second water tank is set higher than the height of the first water tank,
The connection part with the said 1st water storage tank of the said treated water circulation piping is provided with the upright part of the reverse U shape of the height corresponded to the water level of the said 2nd water storage tank raised up. The conductivity reduction system according to claim 1 . The conductivity reduction system according to claim 1 or 2 , wherein the treated water is pure water used as a primary cooling water of a primary cooling system of a nuclear power plant. A first water storage tank that stores treated water produced by treating the raw water with water, a treated water produced by treating the treated water in the first water storage tank with water, and a second that is opened to the atmosphere. A method for reducing conductivity, which is used in a treated water production line including a water storage tank and reduces the conductivity of treated water stored in the second water storage tank,
An overflow pipe extending to the drainage groove is connected to the second water storage tank, and the inside of the second water storage tank is opened to the atmosphere through the overflow pipe.
The treated water produced by treating the treated water in the first water storage tank with a desalination apparatus having a cartridge-type ion exchange resin that can be attached and detached and stored in the second water storage tank is used as the second water storage tank. The water stored in the second water storage tank is repeatedly flown toward the first water storage tank by the head pressure between the first water storage tank and the first water storage tank. A method for reducing electrical conductivity, comprising reducing the electrical conductivity of water.

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